The present disclosure relates to wireless communication systems, and more particularly, to a method and an apparatus for enabling a quick repeat feature.
A wireless communication system is a complex network of systems and elements. Typical systems and elements include (1) a radio link to mobile stations (e.g., a cellular telephone or a subscriber equipment used to access the wireless communication system), which is usually provided by at least one and typically several base stations, (2) communication links between the base stations, (3) a controller, typically one or more base station controllers or centralized base station controllers (BSC/CBSC), to control communication between and to manage the operation and interaction of the base stations, (4) a switching system, typically including a mobile switching center (MSC), to perform call processing within the system, and (5) a link to the land line, i.e., the public switch telephone network (PSTN) or the integrated services digital network (ISDN).
A base station sub system (BSS) or a radio access network (RAN), which typically includes one or more base station controllers and a plurality of base stations, provides all of the radio-related functions. The base station controller provides all the control functions and physical links between the switching system and the base stations. The base station controller is also a high-capacity switch that provides functions such as handover, cell configuration, and control of radio frequency (RF) power levels in the base stations.
The base station handles the radio interface to the mobile station. The base station includes the radio equipment (transceivers, antennas, amplifiers, etc.) needed to service each communication cell in the system. A group of base stations is controlled by a base station controller. Thus, the base station controller operates in conjunction with the base station as part of the base station subsystem to provide the mobile station with real-time voice, data, and multimedia services (e.g., a call).
After a call is established (i.e., after service negotiation between the base station subsystem and the mobile station) and also throughout the call itself, for example, the base station subsystem may provide the mobile station with extended supplemental channel assignment messages (ESCAM) which include information such as when the mobile station may communicate with the base station subsystem and at what rate to do so. In particular, the base station controller sends a reverse ESCAM via the base station to the mobile station to indicate the time and the rate that the mobile station may transmit data to the base station. In contrast, the base station controller sends a forward ESCAM via the base station to the mobile station to indicate the time and the rate that the base station may transmit data to the mobile station.
To ensure that the mobile station receives the operating information in the ESCAM so that the mobile station operates properly, a quick repeat feature may be performed by the base station subsystem. That is, the base station controller generally transmits an ESCAM for a given number of times prior to processing data based on the ESCAM. For example, the base station controller may transmit a first ESCAM (e.g., a reverse ESCAM) for three times, which typically takes 320 milliseconds (msec). A second ESCAM (e.g., a forward ESCAM) may be stored in a queue until after the base station subsystem processes the three transmissions of the first ESCAM because the base station subsystem and the mobile station typically process only one ESCAM at a time. Thus, the second ESCAM may be late arriving to the mobile station which, in turn, may cause radio link protocol (RLP) resets (i.e., when data has been lost and an unsuccessful attempt to recover the lost data in a radio link) and low throughput. As a result of each RLP reset, the amount of processed data may be reduced.
One aspect of designing a wireless communication system is to optimize the resources available to the wireless communication system. That is, one method of improving the availability of resources is to reduce the amount of overhead bandwidth used, and the amount of power used for processing ESCAMs. As described in the above example, a base station controller may provide an ESCAM three times to the mobile station. However, the mobile station may be in good RF condition (i.e., little or no fading) and therefore, may not necessarily need three opportunities to receive the ESCAM. In other words, the mobile station may receive the first transmission of the ESCAM so that the second and third transmissions of the ESCAM may not be necessary. As a result, the overhead bandwidth and the processing power of the base station controller, the base station, and the mobile station may not be efficiently utilized.
Therefore, a need exist to control transmission of an operating message to optimize communication resources of a wireless communication system.